Blog too large to export?

I’m trying to export history.studentreader.com so I can import it into studentreader.cm and have everything more centralized. Unfortunately this is not working! I’ve read the forums but haven’t found solutions that have worked for me. I’ve tried the follow, and combinations thereof:

1) Removing .htaccess and creating a new one
2) Removing php.ini and creating a new one
3) Increasing the resource limits in php.ini
4) Setting my permalinks to default.

But I always get a 500 Server Error, as though it is timing out or something. As you can see the site that I am exporting has lots of categories and about 800 posts. My host is HostMonster, and has helped me troubleshoot but so far I still cannot export.

I’ve had no problem exporting and importing my other ***.studentreader.com blogs, but these were much smaller.

500 Server Error

A misconfiguration on the server caused a hiccup. Check the server logs, fix the problem, then try again.
URL: https://history.studentreader.com/wp-admin/export.php?download=true&content=all&cat=0&post_author=0&post_start_date=0&post_end_date=0&post_status=0&page_author=0&page_start_date=0&page_end_date=0&page_status=0&submit=Download+Export+File